Through screening using an antibody to a polypeptide that constitutes a parasporal body in sporangia of Bacillus popilliae and has a larvae growth inhibiting or insecticidal effect on a Scarabaeidae insect and through polymerase chain reaction, polynucleotides encoding the polypeptide and polypeptides similar thereto are isolated.
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This application is a Divisional of prior application Ser. No. 10/120,544, now U.S. Pat. No. 7,033,993, filed on Apr. 12, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to polypeptides having larvae growth inhibiting or insecticidal effect on Scarabaeidae insects, to polynucleotides encoding the same, to controlling agents for controlling Scarabaeidae insects containing the polypeptides as active ingredients, and to a method of controlling Scarabaeidae insects using the polypeptides.
2. Description of the Related Art
Larvae of Scarabaeidae insects eat roots of a wide variety of plants such as turf, agricultural crops, horticultural crops and trees and bushes and cause serious damage thereto. A large number of reports have been made on damages caused by, especially, Anomala cuprea, Blitopertha orientalis, and Popillia japonica to a lawn of golf courses, a sweet potato field, and a peanut field. In particular, Anomala cuprea, which is particularly large in size, does considerable harm thereto due to its eager appetite.
However, conventional ground spreading of chemical pesticides is difficult to give a controlling effect since these larvae inhabit in the ground and are difficult to locate them, and thus it was necessary to spread a large amount of chemical pesticides over a wide range of the surface of the ground and penetrate them into the ground. Therefore, there were concerns about adverse influences of the chemical pesticides on the natural environment and human bodies, and there has been a keen desire for a biological controlling method that can replace the chemical pesticides.
As one of the biological controlling methods for controlling Scarabaeidae insects, attempts to utilize bacteria belonging to Bacillus popilliae have been tried over a long period of time. The bacteria are parasitic to larvae of Scarabaeidae insects as hosts and infect to them per os usually in a form of sporangia, propagate in large amounts in hemolymph to cause milky disease and finally lead the larvae to death.
Recently, an amino acid sequence of a polypeptide constituting a parasporal body of a strain belonging to Bacillus popilliae, i.e., Bacillus popilliae subsp. melolonthae H1, and a nucleotide sequence of the gene encoding the polypeptide were partly clarified (J. Bacteriol. Vol. 179, p.4336-4341 (1997)), and it has been reported that the polypeptide constituting the parasporal body of Bacillus popilliae subsp. melolonthae H1 has a controlling effect on Melolontha melolontha (WO97/14798). However, it was not clarified whether the bacterial strain and a polypeptide thereof have controlling effects on Anomala cuprea, Blitopertha orientalis and Popillia japonica, each of which belongs to different species.
An object to be solved according to the present invention is to provide polypeptides having a larvae growth inhibiting effect or an insecticidal effect on Scarabaeidae insects, in particular Anomala cuprea, Blitopertha orientalis and Popillia japonica, transformants having introduced therein a polynucleotide encoding the polypeptide, controlling agents for Scarabaeidae insects containing the polypeptides as active ingredients, controlling agents for Scarabaeidae insects using the polypeptide and sporangia of Bacillus popilliae, and a method of controlling Scarabaeidae insects using the controlling agents.
The inventors of the present invention have found that the sporangia of certain strains belonging to Bacillus popilliae have a larvae growth inhibiting effect or an insecticidal effect. Subsequently, they have taken out the parasporal body from sporangia of Bacillus popilliae (
Therefore, according to the present invention, there is provided (1) a polypeptide having the amino acid sequence of SEQ ID NO: 2, or the amino acid sequence including substitution, deletion or insertion of one or several numbers of amino acid residues and having a larvae growth inhibiting or insecticidal effect on a Scarabaeidae insect.
According to the present invention, there is provided (2) a polypeptide having the amino acid sequence of SEQ ID NO: 4, 6, 18 or 20, or the amino acid sequence including substitution, deletion or insertion of one or several numbers of amino acid residues, the polypeptide having a larvae growth inhibiting or insecticidal effect on a Scarabaeidae insect.
According to the present invention, there is provided (3) a polypeptide having the amino acid sequence of SEQ ID NO: 8 or 10, or the amino acid sequence including substitution, deletion or insertion of one or several numbers of amino acid residues, the polypeptide having a larvae growth inhibiting or insecticidal effect on a Scarabaeidae insect.
Further, the present invention provides polynucleotides encoding the polypeptides.
Still further, the present invention provides vectors comprising the polynucleotides and transformants which are introduced the polynucleotides.
Further, the present invention provides controlling agents for controlling a Scarabaeidae insect containing the polypeptides as active ingredients.
Further, the present invention provides controlling agents for controlling a Scarabaeidae insect comprising the polypeptides and sporangia of bacteria belonging to Bacillus popilliae as active ingredients.
Still further, the present invention provides a method of controlling a Scarabaeidae insect, in which the Scarabaeidae insect is subjected to an action of the controlling agent for controlling a Scarabaeidae insect.
In the present invention, the term “polypeptide” includes peptides consisting of a plurality of amino acids linked through peptide bonds and polypeptides to which other molecules such as glycoproteins are bonded as well as proteins in a form of multimers, etc.
According to the present invention, polypeptides having a larvae growth inhibiting or an insecticidal effect on Scarabaeidae insects, in particular Anomala cuprea, Blitopertha orientalis and Popilliae japonica, transformants having introduced therein a polynucleotide encoding the polypeptide, a controlling agent for controlling a Scarabaeidae insect comprising the polypeptide as an active ingredient, and a method of controlling a Scarabaeidae insect using the polypeptide and sporangia of Bacillus popilliae as active ingredients.
Hereinafter, the present invention will be described in detail.
A parasporal body contained in sporangia of a bacterium belonging to Bacillus popilliae is a proteinaceous aggregate (Hukuhara, Toshihiko, “Insect Pathology”, p. 57, 1979), which comprises one kind or plural kinds of polypeptides. The polypeptide of the present invention is one or more polypeptides that constitute the parasporal body in the sporangium of Bacillus popilliae semadara or the like that will be described below. However, the polypeptide of the present invention is different in the amino acid sequence from a polypeptide that constitutes a parasporal body described in WO97/14798, and hence the polypeptide and polynucleotide of the present invention are considered to be novel.
According to a first aspect of the present invention, there is provided a polypeptide having the amino acid sequence of SEQ ID NO: 2 and having a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect.
According to a second aspect of the present invention, there is provided a polypeptide having the amino acid sequence of SEQ ID NO: 4, 6, 18 or 20 and having a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect.
According to a third aspect of the present invention, there is provided a polypeptide having the amino acid sequence of SEQ ID NO: 8 or 10 and having a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect.
Note that the amino acid sequence of SEQ ID NO: 2 and the nucleotide sequence of SEQ ID NO: 1 are sequences found in the amino acid sequences of SEQ ID NO: 4, 6, 18 or 20 and the nucleotide sequences of SEQ ID NO: 3, 5, 17 or 19 with homology of 95% or more and is considered to be specific to the parasporal body of Bacillus popilliae (cf. Example 11).
The above-mentioned polypeptide of the present invention may include polypeptides containing substitution, deletion or insertion of one or several numbers of amino acid residues as far as the polypeptides have a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect. Here, the term “several numbers of” means, specifically, a number of from 2 to 100, preferably from 2 to 50, and more preferably from 2 to 9, although it may vary depending on the position and kinds of amino acid residues in a three-dimensional structure of the polypeptide. These polypeptides including substitution, deletion or insertion of one or several numbers of amino acid residues can be obtained, for example, by introducing a mutation to a polynucleotide encoding the polypeptide by site-specific mutatagenesis and performing transcription and translation of the polynucleotide. These polypeptides of the present invention may be fused polypeptides with other polypeptides. The polypeptides of the present invention may be polypeptides that have the amino acid sequence having homology of 50% or more, preferably 70% or more, and more preferably 90% or more, with the above-mentioned amino acid sequence as far as the polypeptides have a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect. Further, the polypeptides of the present invention may be polypeptides that have a part of the amino acid sequence of SEQ ID NO: 4, 6, 18 or 20 as far as the polypeptides have a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect.
The polynucleotides of the present invention are polynucleotides that encode the above-mentioned polypeptides of the present invention. Codons of each of amino acid residues are not particularly limited as far as the amino acid sequence encoded is the same. Specific examples of the polynucleotide of the present invention include a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1, a polynucleotide having the nucleotide sequence of the coding region of SEQ ID NO: 3, 5, 17 or 19, and a polynucleotide having the nucleotide sequence of SEQ ID NO: 7 or 9.
The polynucleotide of the present invention may be a polynucleotide that is hybridizable under the stringent conditions to each of the above-mentioned polynucleotide or a probe that can be prepared from the above-mentioned polynucleotide as far as they encode polypeptides having a larvae growth inhibiting effect or an insecticidal effect on a Scarabaeidae insect. The term “the stringent conditions” used herein refers to a condition under which a so-called specific hybrid is formed and nonspecific hybrid is not formed. Such a condition is a condition in which DNAs having high homology, for example, DNAs having homology of 50% or more, preferably 70% or more, and more preferably 90% or more, are hybridized and DNAs having homology that is lower than the above are not hybridized. Specifically, it includes a condition of 40° C., 1×SSC (0.15 M NaCl, 15 mM Sodium Citrate, pH 7.0) and 0.1% SDS (Sodium Dodecyl Sulfate).
The polynucleotides of the present invention can be obtained from, for example, bacteria belonging to Bacillus popilliae, more specifically from Bacillus popilliae semadara, FERM P-16818, Bacillus popilliae var. Mame, FERM P-17661, Bacillus popilliae var. popilliae Hime, FERM P-17660, Bacillus popilliae var. popilliae Sakura, FERM P-17662, and Bacillus popilliae Dutky, American Type Culture Collection No. 14706 by the following methods.
Bacillus popilliae semadara, FERM P-16818 has been deposited by Chiba-ken (1-1, Ichiba-cho, Chuo-ku, Chiba-shi, Chiba-ken, Japan) since May 21, 1998 in National Institute of Bioscience and Human Technology of Agency of Industrial Science and Technology of Ministry of International Trade and Industry (1-3 Hagashi 1-Chome, Tasukuba-shi, Ibaraki-ken 305-8566 Japan) (currently, National Institute of Advanced Industrial Science and Technology International Patent Organism Depository, Tsukuba Central 6, 1-1, Hagashi 1-Chome, Tsukuba-shi, Ibaraki-ken, 305-8566, Japan), and the original deposit was converted to international deposit based on the Budapest Treaty on Jun. 10, 2002, and assigned the deposition number of FERM BP-8068.
Bacillus popilliae var. Mame. FERM P-17661 has been deposited by the applicant of the application since Nov. 25, 1999 in National Institute of Bioscience and Human Technology of Agency of Industrial Science and Technology of Ministry of International Trade and Industry (1-3, Hagashi 1-Chome, Tsukuba-shi, Ibaraki-ken, 305-8566, Japan) (currently, National Institute of Advanced Industrial Science and Technology, International Patent Organism Depository, Tsukuba Central 6, 1-1, Hagashi 1-Chome, Tsukuba-shi, Ibaraki-ken, 305-8566, Japan), and the original deposit was converted to international deposit based on the Budapest Treaty on Jun. 10, 2002, and assigned the deposition number of FERM BP-8069.
One method of obtaining them includes a screening method by utilizing an antibody. That is, an antibody to a purified parasporal body is prepared in advance. On the other hand, a chromosomal DNA of the above-mentioned bacterial strain is collected, cleaved with an appropriate restriction enzyme and inserted into an expression vector to prepare a chromosomal DNA library. Then, the library is expanded in Escherichia coli or the like and screened by Western blotting utilizing the above-mentioned antibody.
Another method of obtaining the polynucleotides of the present invention includes a PCR method. An appropriate nucleotide sequence is selected from nucleotide sequences of SEQ ID NOs: 11 to 16, 21 and 22 and nucleotide sequences obtained by adding modifications thereto and partial nucleotide sequences derived from the nucleotide sequences of SEQ ID NOs: 1, 3, 5, 7, 9, 17 and 19, and two kinds of polynucleotides directing opposite to each other are provided. PCR is performed using the polynucleotides as primers and a chromosomal DNA as a template. By cloning an amplified DNA fragment, the polynucleotides of the present invention can be obtained.
Note that PCR using oligonucleotides having respective nucleotide sequences of SEQ ID NOS: 11 and 13 as primers and a chromosomal DNA of Bacillus popilliae semadara as a template can give rise to polynucleotide amplified fragments of about 4.2 kb having the nucleotide sequences of SEQ ID NOS: 17 and 19, respectively. The nucleotide sequences of these polynucleotides exist adjacent to each other on the chromosomal DNA of Bacillus popilliae semadara and the amino acid sequences (SEQ ID NOS: 18 and 20) of the polypeptides encoded by the polynucleotides have homology of about 73% to each other, which strongly suggests that both the polynucleotides have similar functions.
Also, the polynucleotides having the nucleotide sequences of SEQ ID NOS: 3, 5, 7, and 9 obtained by PCR using a chromosomal DNA of Bacillus popilliae var. popilliae Mame as a template and polypeptides having amino acid sequences of SEQ ID NOS: 4, 6, 8 and 10, which are translation products thereof, have high homology to the nucleotide sequence of the polynucleotide of Bacillus popilliae semadara and the polypeptide encoded by the polynucleotide (homology of 61 to 88% for the polynucleotide and 59 to 98% for the polypeptide). This suggests that they also have similar functions.
Further, another method of obtaining the polynucleotides of the present invention includes a hybridization method. After digesting the chromosomal DNA with an appropriate restriction enzyme, a genome library is prepared by utilizing a plasmid vector or a phage vector or the like. On the other hand, appropriate polynucleotide probes having the nucleotide sequences of SEQ ID NOS: 11 to 16, 21 and 22 or nucleotide sequences obtained by adding modifications thereto, or partial nucleotide sequences derived from the nucleotide sequences of SEQ ID NOS: 1, 3, 5, 7, 9, 17 and 19 are provided. By colony hybridization or plaque hybridization in which a library prepared in Escherichia coli or the like by using the vector is screened with a labeled probe, the polynucleotide of the present invention can be obtained.
The vectors that can be used in the present invention include plasmid vectors, Ti plasmid vectors, phage vectors, phagemid vectors, YAC vectors, virus vectors and the like. The vectors may include, in addition to the polynucleotides of the present invention, sequences that regulate or assist expression of polypeptides (for example, a promoter, an operator, a terminator, an enhancer, and an SD sequence) or marker gene for selecting transformant hosts (for example, an ampicillin resistance gene, a tetracycline resistance gene, a kanamycin resistance gene, and a neomycin resistance gene) and the like. The vectors may comprise plural kinds of polynucleotides of the present invention or a plurality of molecules of the same polynucleotide.
The hosts that can be used in the present invention include microbes (for example, bacteria such as Escherichia coli, Pseudomonad, and Bacillus, actinomycetes such as Streptomyces, Fungi such as molds and yeasts), plants (for example, turf, sweet potatoes, tobaccos, rice plants, and corn), cultured cells (for example, plant cultured cells such as a tobacco cultured cell, insect cultured cells such as a silkworm moth cultured cell and animal cultured cells such as mouse cultured cell) and the like.
In the present invention, conventional methods used in genetic engineering can be used in the procedure of constructing a vector and transformation operation of hosts with the vector. For example, the transformation method includes a calcium chloride method, an electroporation method, a PEG method and the like for microbe hosts, an electroporation method, a particle gun method, an agrobacterium method and the like for cultured cells and plant hosts.
In a case where the host is a microbe or a cultured cell, the method of producing a polypeptide of the present invention can be performed by culturing the microbe or the cultured cell in an appropriate medium and recover the produced polypeptide from the culture. The culture method of culturing a transformed host may be substantially the same as the culture method for the host to be used. Extraction of the polypeptide from the culture and purification thereof, if necessary, may be performed by usually employed methods. On the other hand, in a case where the host is a plant, the transformed plant is grown by the same methods as the methods usually used, and a polypeptide can be extracted from the plant body. From a different standpoint, the transformed plant and its seeds may be provided as is as insect resistant cultigen species. In addition, there is a production method of a polypeptide without using any transformant. It includes, for example, an in vitro cell-free transcription/translation system utilizing a wheat germ extract or an Escherichia coli extract. A polypeptide can be produced by adding a DNA fragment or an RNA fragment, or a vector containing the polynucleotide of the present invention to the transcription/translation system, thereby performing a conventional method for producing a polypeptide.
The polypeptides of the present invention have a larvae growth inhibiting or insecticidal activity on Scarabaeidae insects and exhibit controlling effects thereon. For this reason, the polypeptides can be applied to turf, agricultural crops or trees as a controlling agent or an active ingredient thereof for the purpose of controlling Scarabaeidae insects. Use of the polypeptides of the present invention in combination with spores or sporangia containing spores and parasporal bodies of bacteria belonging to Bacillus popilliae can further increase the larvae growth inhibiting or insecticidal activity on Scarabaeidae insects.
The Scarabaeidae insects that are the target of control with the polypeptides of the present invention include Anomala cuprea, Blitopertha orientalis, Popillia japonica, Phyllopertha diversa, Adoretus tenuimaculatus, Anomala rufocuprea and the like. The polypeptides of the present invention are particularly effective on Anomala cuprea and Blitopertha orientalis.
As the controlling agent of the present invention, the polypeptides produced by the above-mentioned production method may be used as they are in the form of the transformants, as a purified product after isolation or as mixtures of these with substances used for culture/reaction systems of these. Alternatively, they may be used by adding excipients, carriers, nutritive agents, stabilizers and the like known and commonly used in agricultural chemicals to convert them into an optional preparation form such as dust, wettable powder, or a flowable agent.
The above-mentioned optional component includes: mineral fine powders such as kaolin clay, bentonite, montmorillonite, diatomaceous earth, acid clay, talcs, pearlite, and vermiculite, inorganic salts such as ammonium sulfate, urea, ammonium chloride, and ammonium nitrate, organic fine powders such as wheat bran, chitin, polysaccharides, rice bran, and flour, as solid carriers; fixing agents and dispersants such as casein, gelatin, gum Arabic, alginic acid, saccharides, synthetic polymers (polyvinyl alcohol, polyacrylic acids, etc.) as adjutants; and cryoprotectants such as propylene glycol and ethylene glycol, natural polysaccharides such as xanthan gum, thickeners such as polyacrylic acids as other components.
The ratio of the polypeptides of the present invention contained in the controlling agent is not particularly limited as far as they exhibit a controlling effect on Scarabaeidae insects, but it is preferably 0.0001 to 100 mass %.
The method of application of the controlling agent is selected as appropriate depending on the use form such as the preparation form, crops and the like and includes, for example, liquid dispersion on the ground, solid dispersion on the ground, liquid dispersion in the air, solid dispersion in the air, application in installations, application for mixing with soil, application for perfusion into soil, and the like methods.
Also, it is possible to apply the controlling agent of the present invention after mixing with other agents, i.e., pesticides, nematicides, acaricides, herbicides, microbicides, plant growth regulators, fertilizers, soil conditioning materials (peat, humic acid materials, polyvinyl alcohol-based materials, etc.) and the like, to apply it with alternately applying the other agents without mixing, or to apply it together with the other agents simultaneously.
The application amount of the controlling agent of the present invention cannot be uniquely defined since it may vary depending on the kind of Scarabaeidae insect, kind of plant to which the agent is applied, preparation form of the agent and the like. For example, the application amount of the polypeptide may be 0.01 to 100 g/m2, preferably about 0.1 to 50 g/m2 for dispersion on the ground.
Further, it is possible to use mixtures of the controlling agent of the present invention with other biocontrol agents or polypeptides derived from microbes (for example, the parasporal bodies of another strain of Bacillus popilliae or the parasporal bodies of Bacillus thuringiensis) or microbial spores (for example, spores of Bacillus popilliae, Bacillus thuringiensis, or Bacillus subtilis).
Hereinafter, the present invention will be illustrated more specifically. However, the scope of the present invention is not limited thereto.
A suspension of sporangia of Bacillus popilliae prepared from larvae of Anomala cuprea infected with milky disease was subjected to treatment by a French press to take out spores and parasporal bodies from the sporangia. Only the parasporal bodies were recovered by a two-phase separation method by using sodium dextran sulfate (produced by Sigma Co., Ltd.), polyethylene glycol 6000 (produced by Wako Pure Chemical Industry Co., Ltd.) and NaCl and solubilized with 0.1 M NaOH and then subjected to SDS-PAGE. An about 135 kD band was cut out and pulverized to small pieces, which then were mixed with an adjuvant. The mixture was intradermally injected to a rabbit to immunize it.
To decrease the background upon screening a polypeptide gene clone that constitutes the parasporal body by using an antibody, absorption operation of the obtained antiserum with Escherichia coli fragments was repeated three times to remove the antibody that adsorbs on Escherichia coli itself and collect only the antibody that adsorbs on the polypeptide constituting the target parasporal body.
A chromosomal DNA was collected from the bacterial cells of Bacillus popilliae semadara by an ordinary method and digested with restriction enzyme EcoRI. This was ligated to phosphatase-treated pBluescript SK(+) and Escherichia coli DH5α was transformed with the ligation product. The transformants were spread over the LB agar plate so that 2,000 to 3,000 colonies could appear thereon.
A nitrocellulose membrane was closely contacted on the agar plate to transfer colonies on the membrane and the membrane was placed on a fresh agar plate so that the colonies-attached side of the membrane directs upward. The plate was incubated at 37° C. for 2 hours. For bacteriolysis of the bacterial cells on the membrane, the following operation was performed. That is, the membrane was transferred on a filter paper impregnated with 10% SDS and left to stand for 5 minutes. Then, the membrane was transferred on a filter paper impregnated with 0.2 M NaOH, 0.15 M NaCl and 1% β-mercaptoethanol and left to stand for 5 minutes and finally it was transferred on a filter paper impregnated with 0.15 M NaCl, 0.5 M Tris-HCl, and pH 7.5, and left to stand for 10 minutes. The membrane was transferred to a buffer solution (0.1 M Tris-HCl, pH 7.8, 0.15 M NaCl, 5 mM MgCl2, 40 μg/ml lysozyme, and 5% skimmed milk) and shaken for 2 hours to remove the bacterial cells.
After washing the membrane with TBST (0.02 M Tris-HCl, pH 7.2, 0.5 M NaCl, and 0.05% Tween 20) for 5 minutes, the membrane was shaken for 1.5 hours in an anti-parasporal body antiserum solution diluted 8,000 folds with an antibody diluting liquid (TBST containing 5% skimmed milk). After repeating 10 minutes' washing with TBST three times, the membrane was transferred into a solution of 2,000-fold diluted Anti-Rabbit IgG (H&L), HRP-Linked (produced by New England Biolabs, Inc.) and incubated until color development was observed in an HRP coloring substrate (4CN, produced by NEN Life Science Products Co.).
Colonies near a site where strong coloring was observed, that is, to which the anti-parasporal body antiserum was adsorbed, were collected one by one from the master plate and the collected colonies were subjected to secondary screening performed in the same manner as described above to obtain a positive clone.
Plasmid was collected from the positive clone and the nucleotide sequence of the inserted portion was determined by an ordinary method. As a result, it revealed that the plasmid contained two polypeptide genes, which constitute the parasporal body of Bacillus popilliae, (SEQ ID NOS: 17 and 19, respective translation products being of SEQ ID NOS: 18 and 20) in a single cloned fragment. The amino acid sequence of SEQ ID NO: 18 and that of SEQ ID NO: 20 have about 73% of homology to each other. In this case, gene information processing software GENETYX-WIN (Software Development Co., Ltd.) is used for retrieval of the homology.
PCR was performed by using the plasmid of the above-mentioned positive clone as a template and polynucleotides having nucleotide sequences corresponding to parts of a polynucleotide of SEQ ID NO: 19 and a complementary strand thereof (SEQ ID NOS: 21 and 22, respectively) as primers. After electrophoresing the reaction solution, about 4 kb of amplified fragments were recovered and purified and digested with restriction enzymes EcoRI and PstI. The digested products were ligated to a vector pTrc99A (produced by Amersham Pharmacia Biotech Co., Ltd.) that had been digested with EcoRI and PstI in advance, and Escherichia coli BL21(DE3) was transformed with the reaction solution. The transformants obtained were shake-cultured overnight in a 2×YT liquid medium containing 50 mg/l of ampicillin and then IPTG (isopropyl β-D-thiogalactopyranoside) was added so as to bring the transformants to a final concentration of 1 mM, followed by further culture for 2 hours. Observation with a microscope indicated formation of an inclusion body in the cells. Therefore, the clone was named as an expression clone (1).
In a 2-liter baffled Erlenmeyer flask was charged 750 ml of a 2×YT liquid medium containing 50 mg/l of ampicillin and the expression clone (1) obtained in Example 3 was inoculated therein. The medium was shake-cultured at 37° C. 16 hours afterwards, IPTG is added to the medium so as to bring it to a final concentration of 1 mM, and the medium was further cultured for 2 hours. The cultured medium was centrifuged to recover from the culture solution bacterial cells, which were washed with a 10 mM potassium phosphate buffer solution, pH 7.0. Again the suspension was centrifuged to recover the bacterial cells, which were suspended in the above-mentioned buffer solution to finally make it into 120 ml.
10 g per cup of leaf mold was measured out and charged in 40 plastic-made food cups of 6 cm in diameter. In 20 cups out of them was dispersed 1 ml per cup of the suspension of the expression clone (1) and 1 ml per cup of water as blank was dispersed in the remaining 20 cups, followed by well mixing. In each of the food cups, one first instar larva of Anomala cuprea was released and fed under a condition of 25° C. Mortality of the larvae and mean body weight of the surviving larvae were measured with a lapse of time to verify the insecticidal activity and larvae growth inhibiting activity of the expression clone (1).
The results are shown in Table 1 and
TABLE 1
Cumulative Mortality (%)
test lot
1st week
2nd week
3rd week
4tn week
5th week
Expression
5.0
45.0
65.0
80.0
95.0
clone
Blank
5.0
5.0
5.0
5.0
5.0
In a 2-liter baffled Erlenmeyer flask was charged 750 ml of a 2×YT liquid medium containing 50 mg/l of ampicillin and the expression clone (1) obtained in Example 3 was inoculated therein. The medium was shake-cultured at 37° C. After 16 hours, IPTG was added so as to bring the medium to a final concentration of 1 mM and the medium was further cultured for 2 hours. The culture medium was centrifuged to recover from the culture solution bacterial cells, which were washed with a 10 mM potassium phosphate buffer solution, pH 7.0. Again the suspension was centrifuged to recover the bacterial cells, which were suspended in the above-mentioned buffer solution to finally make it into 75 ml, thus making it as an expression clone suspension.
On the other hand, the sporangia of Bacillus popilliae semadara were collected from larvae of Anomala cuprea infected with milky disease and washed with water. They were suspended again in water to a density of 8×107 sporangia/ml to make it as a sporangia suspension.
80 plastic-made food cups of 6 cm in diameter, each of which was charged with 25 g of leaf mold that was measured out, were prepared. In 20 cups out of them was dispersed 1 ml per cup of the suspension of the expression clone (1), in other 20 cups was dispersed 0.5 ml per cup of the sporangia suspension, in still other 20 cups was dispersed 1 ml of the expression clone suspension together with 0.5 ml of the sporangia suspension, and in the remaining 20 cups was dispersed 1 ml per cup of water, followed by well mixing. In each of the food cups, a second instar larva of Anomala cuprea was released one by one and fed under a condition of 25° C. for 21 days. Mortality of the larvae and mean body weight of the surviving larvae were measured with a lapse of time to verify synergistic effects in the insecticidal activity and the larvae growth inhibiting activity of the expression clone (1) used in combination with the sporangia.
The results are shown in
Polynucleotides having the nucleotide sequences of SEQ ID NO: 11 and SEQ ID NO: 13 corresponding to parts of complementary strands of SEQ ID NO: 17 and SEQ ID NO: 19, respectively, were prepared by chemical synthesis. PCR performed by using the polynucleotides as primers and a chromosomal DNA of Bacillus popilliae semadara as a template indicated amplification of about 4.2 kb fragments. TA cloning of the fragments gave rise to a number of clones, some of which were subjected to determination of the nucleotide sequence of the insert portion by sequencing. As a result, polynucleotides having the nucleotide sequences of SEQ ID NO: 17 and SEQ ID NO: 19 were obtained. Therefore, it revealed that the polynucleotide of the present invention can also be obtained by PCR using the polynucleotides having the nucleotide sequences of SEQ ID NO: 11 and SEQ ID NO: 13, respectively.
A chromosomal DNA was collected from the bacterial cells of Bacillus popilliae var. popilliae Mame by an ordinary method. On the other hand, based on the nucleotide sequence of the gene encoding the polypeptide constituting the parasporal body of Bacillus popilliae semadara as a reference, polynucleotides having the nucleotide sequences of SEQ ID NO: 11 and SEQ ID NO: 14, respectively, were chemically synthesized. PCR performed using the polynucleotides as primers and the chromosomal DNA as a template indicated amplification of about 4.3 kb fragments. TA cloning of the fragments gave rise to a number of clones, one of which was subjected to determination of the nucleotide sequence of the insert by sequencing. As a result, a polynucleotide having the nucleotide sequence of SEQ ID NO: 3 was obtained. This was further translated to obtain the amino acid sequence of SEQ ID NO: 4.
Polynucleotides having nucleotide sequences of SEQ ID NO: 12 and SEQ ID NO: 13, respectively, were prepared by chemical synthesis. PCR performed by using the polynucleotides as primers and the chromosomal DNA prepared as described above as a template indicated amplification of about 4.2 kb fragments. TA cloning of the fragments gave rise to a large number of clones, one of which was subjected to determination of the nucleotide sequence of the insert portion by sequencing. As a result, a polynucleotide having the nucleotide sequence of SEQ ID NO: 5 was obtained. This was further translated to obtain the amino acid sequence of SEQ ID NO: 6.
Polynucleotides having the nucleotide sequence of SEQ ID NO: 15 corresponding to a part of a complementary strand of SEQ ID NO: 3 and the nucleotide sequence of SEQ ID NO: 11, respectively, were prepared by chemical synthesis. PCR performed by using the polynucleotides as primers and the chromosomal DNA prepared as described above as a template indicated amplification of about 1.2 kb fragments. TA cloning of the fragments gave rise to a large number of clones, one of which was subjected to determination of the nucleotide sequence of the insert portion by sequencing. As a result, a polynucleotide having the nucleotide sequence of SEQ ID NO: 7 was obtained. This was further translated to obtain the amino acid sequence of SEQ ID NO: 8.
The chromosomal DNA obtained as described above was degested with restriction enzyme XhoI and the fragments were ligated with SalI Cassette contained in a LA PCR in vitro Cloning Kit produced by Takara Shuzo Co., Ltd. On the other hand, a polynucleotide having the nucleotide sequence (SEQ ID NO: 16) corresponding to a part of a sequence of SEQ ID NO: 3 was prepared by chemical synthesis. Then, PCR was performed by using the polynucleotide and a Cassette primer C1 attached to the Kit as primers and the ligated chromosomal DNA fragment as a template. As a result, amplification of about 3 kb fragments was observed. TA cloning of the fragments gave rise to a large number of clones, one of which was subjected to determination of the nucleotide sequence of the insert portion by sequencing. As a result, a clone having a polynucleotide having the nucleotide sequence of SEQ ID NO: 9 coupled in tandem to downstream of the latter half of the nucleotide sequence of SEQ ID NO: 3 was obtained. The nucleotide sequence of SEQ ID NO: 9 was further translated to obtain the amino acid sequence of SEQ ID NO: 10.
The amino acid sequences of the polypeptides of the parasporal bodies existing in Bacillus popilliae obtained in Examples 2, 7 and 8 and the nucleotide sequences of the polynucleotides encoding them were comparatively studied by using gene information processing software GENETYX-WIN (Software Development Co., Ltd.). As a result, sequences that have very high homology of 98% or more in the amino acid sequence and are considered to be specific to the parasporal body of Bacillus popilliae, i.e., the amino acid sequence of SEQ ID NO: 2 and the corresponding nucleotide sequence of SEQ ID NO: 1 were found. The portions indicated by an arrow in
Note that these sequences have homology of 9% or less in the amino acid sequence to the sequence isolated from Bacillus popilliae subsp. Melolonthae H1 described in WO97/14798, and hence is completely different therefrom.
PCR was performed by using a chromosomal DNA of Bacillus popilliae var. popilliae Mame as a template and polynucleotides of SEQ ID NO: 12 and SEQ ID NO: 14 as primers to amplify about 4 kb fragments, which were purified and recovered by electrophoresis and subsequent cutting out. The fragments were ligated to a pT7Blue vector (Novagen, Inc.) and Escherichia coli DH5α was transformed with the ligation product. Among the obtained clones, a clone harboring the pT7Blue with the 4 kb insert downstream of lac promoter in a direction of sense to form a fusion polypeptide with an N-terminal portion of a lacZ polypeptide was selected. This was named as an expression clone (2) and used in the following tests of production of a polypeptide and effects thereof.
Ten 300 ml-capacity Erlenmeyer flasks containing 200 ml of a 2×YT medium were prepared. In 5 flasks out of them was inoculated the expression clone (2) obtained in Example 12 and shake-cultured at 37° C. overnight. As a comparative control clone, Escherichia coli DH5α having a pT7Blue vector having inserted therein no 4 kb fragment was inoculated in the remaining 5 flasks and cultured in the same manner as the above. After completion of the culture, bacterial cells were observed with a microscope. As a result, formation of inclusion body in the bacterial cells was observed only in the case of the expression clone (2). The bacterial cells were once recovered from each flask by centrifugation and after washing with water, the bacterial cells were centrifuged again to recover them and then suspended in water to finally make it into 23 ml.
20 g per cup of leaf mold was measured out and charged in 15 plastic-made food cups of 6 cm in diameter. In 5 cups out of them was added a suspension of the expression clone and in other 5 cups out of them was added a suspension of the comparative control clone, followed by well mixing. In the remaining 5 cups was dedicated to blank tests of no addition. In each of the food cups, one first instar larva of Anomala cuprea was released and fed under a condition of 25° C. The body weights of larvae were measured with a lapse of time and compared to verify the larvae growth inhibiting activity of the expression clone (2). In contrast to the blank test and the control lot, a lot where the expression clone (2) was added apparently suppressed increase in mean body weight (
Hasegawa, Makoto, Tanaka, Masao, Kimura, Masaharu, Yokoyama, Tomoko, Ehara, Gaku, Nishihashi, Hideji, Aoyagi, Moriichi
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